1. Field of the Invention
The present invention relates to hard disk drives. More particularly, this invention relates to a disk drive including a resilient securing system providing relative movement between side rails and head disk assembly to accommodate side rails engaging guide channels in a chassis.
2. Description of the Prior Art and Related Information
A huge market exists for mass-market host computer systems such as servers, desktop computers, and laptop computers. To be competitive in this market, a hard disk drive must be relatively inexpensive and must accordingly embody a design that is adapted for low cost mass production. In addition, it must provide substantial capacity, rapid access to data, and reliable performance. Numerous manufacturers compete in this expansive market and collectively conduct substantial research and development, at great annual cost, to design and develop innovative hard disk drives to meet increasingly demanding customer requirements.
Each of the various contemporary mass-marketed hard disk drive models provides relatively large data storage capacity, often in excess of 1 gigabyte per drive. To this end, there exists substantial competitive pressure to develop mass-market hard disk drives that have even higher capacities and that provide rapid access to stored data. Another requirement to be competitive in this market is that the hard disk drive must conform to a selected standard exterior size and shape often referred to as a xe2x80x9cform factorxe2x80x9d. Generally, capacity is desirably increased without increasing the form factor, or the form factor is reduced without decreasing capacity.
Satisfying these competing constraints of low-cost, small size, high capacity, and rapid access requires innovation in each of numerous components or subassemblies. Typically, the main subassemblies of a hard disk drive are a head disk assembly and a printed circuit board assembly.
The head disk assembly includes an enclosure including a base and a cover; at least one disk having at least one recording surface; a spindle motor causing each disk to rotate; and an actuator arrangement. The actuator arrangement includes a separate transducer for each recording surface, and is movable to position each transducer relative to the recording surface. The printed circuit board assembly includes circuitry for processing signals and controlling operation of the drive.
The head disk assembly includes a pair of side rails that are mounted to side walls of the enclosure. These side rails are received within guide channels mounted to side surfaces of a chassis into which the hard disk drive is to be inserted. To mount the hard disk drive in the chassis, the side rails of the hard disk drive need to be aligned with the guide channels. Next, the hard disk drive is slid into the chassis such that the side rails of the head disk assembly ride on the guide channels of the chassis. Upon full insertion of the hard disk drive in the chassis, a printed circuit board (PCB) electrical/data connector of the printed circuit board assembly engages a corresponding PCB electrical/data connector on a motherboard or backplane wall of the chassis. A latch arrangement associated with the side rails and guide channels secures the head disk assembly and thereby the hard disk drive within the chassis.
To mount the side rails to the side walls of the head disk assembly, the head disk assembly and a first side rail of the pair of side rails are placed into an assembly jig. The assembly jig aligns fastener openings in the first side rail with threaded fastener apertures in the side wall of the head disk assembly. The threaded fasteners are inserted through the fastener openings in the side rail and then screwed into the threaded fastener apertures. Once the fasteners are appropriately tightened and the first side rail is secured, the assembly jig is flipped 180xc2x0, and the above process is repeated with the second side rail on the opposite side wall of the head disk assembly thereby completing the side rail mounting process. As such, the process of mounting the side rails to the side walls of the head disk assembly can be a time consuming process that results in higher costs for assembling the hard disk drive. Moreover, since the side rail mounting process entails the use of two side rails and at least four threaded fasteners, the cost of providing these components can further increase the cost of the hard disk drive.
While the jig assembly helps to ensure that the side rails are properly aligned (i.e., parallel) with one another, the guide channels of the chassis may not be properly aligned. Unaligned (i.e., non-parallel) guide channels within the chassis may make it difficult to align and insert the side rails of the head disk assembly with and into the guide channels of the chassis. Moreover, since the threaded fasteners secure the side rails to the side walls of the head disk assembly in a fixed position, the side rails can only accommodate (i.e., tolerate) a minute amount of guide channel misalignment. As such, unaligned guide channels can result in a hard disk drive that is virtually impossible to mount within the chassis without some modification of the alignment of the side rails, the guide channels or both. Even if the unaligned guide channels can accept the side rails so that the hard disk drive can be mounted in the chassis, this misalignment can result in unwanted stresses on the side rails and guide channels that may result in hard disk drive affecting failure of one or more of these components.
When both the side rails and the guide channels are properly aligned, insertion of the hard disk drive into the chassis can be accomplished. However, in order to reduce manufacturing costs, the side rails and the guide rails are not manufactured to a high degree of precision. As such, once the hard disk drive is inserted into the chassis some xe2x80x9cplayxe2x80x9d (i.e., movement) may exist between the side rails and the guide channels as a result of this imprecision when manufacturing these components. This xe2x80x9cplayxe2x80x9d, whether side-to-side or up-down, that exits between the side rails and the guide channels can degrade performance of the hard disk drive. Performance of the hard disk drive can be affected by vibration, caused by operation of other components within the chassis, of the hard disk drive that is a result of the play between the side rails and the guide rails. This vibration can be caused by undesirable imbalance in the disk stack and during actuator seeking. Vibration of the hard disk drive can affect performance of the hard disk drive itself and can produce undesirable acoustic noise (i.e., buzzing sound). Moreover, operation of the hard disk drive itself together with the xe2x80x9cplayxe2x80x9d between the side rails and the guide rails can produce mechanical energy that can cause operation and performance affecting vibration in other components such as other disk drives within the chassis.
Accordingly, there is a need for an improved system for mounting side rails to the side walls of a head disk assembly of a hard disk drive. In particular, there is a need for a side rail mounting system that employs less components and reduces the time for mounting the side rails to the head disk assembly, thereby resulting in assembly time and cost savings. In addition the side rail mounting system should improve side rail to guide channel fit so as to reduce play between the side rails and guide channels and acoustic energy. Moreover, the side rail mounting system should be capable of accommodating (i.e., tolerating) some degree of guide channel and/or side rail misalignment (i.e., non-parallelism) so that the hard disk drive can be inserted into the chassis when this condition exists. Lastly, the side rail mounting system should be able to dampen vibration and/or isolate the hard disk drive from vibration so that performance of the hard disk drive is not adversely affected.
The invention can be regarded as a disk drive that is usable in a chassis having first and second guide channels mounted on side surfaces of the chassis for supporting the head disk assembly within the chassis. The disk drive includes a head disk assembly including first and second side walls, first and second side rails, and a securing system for securing the side rails to the side walls. The first and second side rails engage the first and second guide channels, respectively, on the side surfaces of the chassis for supporting the disk drive within the chassis. The securing system includes an engagement means and a double-sided adhesive resilient means. The engagement means protrudes between the first and second side rails and the first and second side walls, respectively, of the head disk assembly. The double-sided adhesive resilient means is adhesively attached between the first side rail and the first side wall and between the second side rail and the second side wall for mounting the first and second side rails to the first and second side walls, respectively, of the head disk assembly. The securing system provides for relative movement between the side rails and the side walls to accommodate the side rails engaging the guide channels in the chassis.
The engagement means and the double-sided adhesive resilient means of the securing system employs less components and reduces the time for mounting the side rails to the head disk assembly of the disk drive resulting in assembly time and cost savings. In addition the securing system improves side rail to guide channel fit by reducing play between the side rails and guide rails and acoustic energy. Moreover, the side rail securing system is capable of accommodating (i.e., tolerating) some degree of guide channel and/or side rail misalignment (i.e., non-parallelism) so that the disk drive can be inserted into the chassis when this condition exists. Lastly, the securing system dampens vibration and isolates the head disk assembly from vibration so that operation and performance of the head disk assembly are not adversely affected.